DESC:FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2005

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

TITLE OF THE INVENTION
“HYBRID FRONT FORK SUSPENSION SYSTEM FOR A TWO-WHEELER”

Endurance Technologies Limited
E-92, M.I.D.C. Industrial Area, Waluj,
Aurangabad – 431136, Maharashtra, India

The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed.

Field of Invention

[001] The present invention is related to suspension system of a two wheeled vehicle. More particularly, the present invention relates to hybrid construction of an inverted front fork suspension system of a two wheeled motor vehicle configured to impart progressive repulsion as required for cushioning, lead elimination of NVH and provide improved reliability.

Background of the Invention

[002] The inverted front fork suspension systems are getting quite popular for the two-wheeled vehicles. As the name suggests, inverted forks (also called upside-down forks or "USD" forks) orient the slider (or fork tube), near the axle, and the outer slider up top, where it clamps into the triple tree. This means the sliding area of the two tubes is greater, the forks have a longer length over which to distribute loads and are more resistant to flex. Also, their outer diameter where they attach to the frame is thicker, so their attachment to the chassis is stronger. For these reasons, inverted forks make the front end of a bike more rigid, which brings good handling and a good feedback from the road as riders can feel chassis rigidity when cornering or braking.

[003] There are a variety of inverted front fork suspension systems available in public domain with varying degree of success as far as its performance is concerned. The inverted front fork suspension system available in the public domain has at least one main spring to absorb the energy transferred from the motor vehicle’s wheel when it encounters a road surface irregularity. It also has at least a damping assembly that dissipates the energy absorbed by the main spring during its compression and expansion. This damping assembly prevents excessive oscillations that would result from undamped compression and expansion of the main spring. Given the difficulty in altering the characteristics of the main spring and the damping assembly to have progressive repulsion as required for cushioning after the inverted front fork is assembled, engineers and/or persons skilled in the art ordinarily have to decide and fix one general purpose setting for both the main spring and the damping assembly. The predefined general purpose setting decides the suitability of driving a vehicle in a given loading and driving surface condition. Hence, it tends to affect the vehicle’s classification as well viz. off-road vehicles, racing vehicles, etc.

[004] The inverted front fork suspension systems available in the public domain fail to address the issues of rebound cushioning and compression cushioning operations and the progressive repulsion as required for cushioning and smooth landing. Hence, there exists a long pending unmet need of providing a hybrid construction of an inverted front fork suspension system that effectively addresses the above stated issues of the prior art and thereby imparts safety to the rider and provides efficient suspension performance at an economic cost.

Objectives of the Invention

[005] The main objective of the present invention is to provide an inverted front fork suspension system for a two wheeled motor vehicle.

[006] Another objective of the present invention is to provide an inverted front fork suspension system wherein the construction of the system is hybrid with one leg having spring based damping and the other leg having magnetic repulsion based damping.
[007] Yet, another objective of the present invention is to provide a hybrid front fork suspension system for a two wheeler that imparts progressive repulsion as required for cushioning and smooth landing and eliminates the issue of noise, vibrations and harshness (NVH).

[008] Still another objective of the present invention is to provide a hybrid front fork suspension system for a two wheeler that leads to improve reliability of the system and the damping life of the forks.

[009] Yet the objective of the present invention is to provide hybrid front fork suspension system for a two wheeler that is easy to manufacture and is an economical solution for low end motor vehicles, particularly less than 100 cc engine.

[0010] Further objective of the present invention is to provide better ride comfort to the user / rider of the vehicle at low cost by providing an efficient inverted front fork suspension system.

Brief Description of the Drawings

[0011] This invention is illustrated in the accompanying drawings, throughout which like reference letters / numerals indicate corresponding parts in the various figures. The embodiments described herein and the advantages thereof will be better understood from the following description when read with reference to the following drawings, wherein

[0012] Figure 1 shows the isometric view of the hybrid inverted front fork suspension system for a two wheeled vehicle in accordance with the present invention.
[0013] Figure 2 discloses the isometric cut view of the hybrid inverted front fork suspension of Fig. 1 in accordance with the present invention.

[0014] Figures 3a and 3b present sectional views of leg A and leg B, respectively of the hybrid inverted front fork suspension system in accordance with the present invention.

[0015] Figures 4a and 4b show sectional view of Leg A and enlarged view of piston assembly marked in Fig. 4a, respectively of the hybrid inverted front fork suspension system in accordance with the present invention.

[0016] Figure 5a shows exploded view of a magnet M1 and its associated coupling member whereas the Figure 5b shows cut view of the assembly of magnet M1 and its associated coupling member as per the present invention.

[0017] Figure 6a shows isometric view of a magnet M2 and its associated sleeve whereas the Figure 6b shows cut view of the assembly of magnet M2 and its associated sleeve as per the present invention.

Description of the Present Invention

[0018] The invention will now be described in detail with reference to the accompanying drawings which must not be viewed as restricting the scope and ambit of the invention. Referring to Figs. 1 to 4, the present invention discloses hybrid structure of an inverted front fork suspension system (500) for two wheeled vehicles. The hybrid structure of front fork suspension system comprises of a pair of fork legs (A and B), a triple clamp bracket / plate (10), and a steering shaft (12). The fork leg (A) has magnets (M1 and M2) arranged therein for the damping performance and the other fork leg (B) of the system has a regular damping system of rebound spring (202) as is generally used in the prior art solutions of inverted front fork assembly. The fork legs (A and B) are joined through the triple clamp bracket (10) to form a hybrid inverted front fork suspension system (500). The steering shaft (12) connects the hybrid assembly of inverted front fork system (500) with the handle bar of a two wheeled vehicle.

[0019] The fork leg (A) of the hybrid suspension system (500) comprises of an outer tube (104), a cartridge tube (106), a fork pipe (108), a spindle (110), a screw cap (112), an adapter (114), an axle clamp (116), a first piston assembly (P1), a second piston assembly (P2), a first magnet (M1) and a second magnet (M2). The outer tube (104) is configured to have a cylindrical profile with an upper end (104U) and a lower end (104L). The upper end (104U) of the outer tube (104) closed with a removable screw cap (112) through a threaded joinery wherein the outer peripheral surface of the screw cap (112) has a plurality of threads thereon and the inner peripheral surface of the upper end (104U) of the outer tube (104) has a plurality of matching threads. The skirt (112S) of the screw cap (112) is configured to have threads on its both the peripheral surfaces i.e. on the inner peripheral surface to get the cartridge (106) fitted therein and on the outer peripheral surface to get the outer tube (104) fitted thereon.

[0020] The cartridge tube (106) is configured to have a cylindrical profile with an upper end (106U) and a lower end (106L). The upper end (106U) of the cartridge tube (106) is configured to have a threaded portion on its outer peripheral surface. The lower end (106L) of the cartridge tube (106) is configured to have a stepped profile (106SP) on its inner peripheral surface. Further, the said stepped profile (106SP) is configured to have a threaded portion (106A), non-threaded portion (106B) and a shoulder (106C). The threaded portion (106A) of the stepped profile starts from the bottom edge of the cartridge and ranges from 40 to 70 per cent of the total length of the stepped profile (106SP). The said non-threaded portion (106B) starts wherein the threaded portion (106A) ends and it goes up to the shoulder (106C).

[0021] The cartridge tube (106) is concentrically placed inside the outer tube (104) and is rigidly fixed with the screw cap (112) at the inner peripheral surface of its skirt (112S) through a threaded joinery. This concentric placement of the cartridge and the outer tube in leg A creates a gap (G) between the outer peripheral surface of the cartridge tube (106) and inner peripheral surface of the outer tube (104) due to variation in their diameters. The cartridge tube (106) is filled with the damping fluid and said damping fluid is selected from the oil, gas, air, etc.

[0022] The fork pipe (108) is configured to have a cylindrical profile with an upper end (108U) and a lower end (108L). The fork pipe (108) is slideably fitted inside the outer tube in such a way that upper end (108U) of the fork pipe (108) is configured to freely travel in the gap (G) between the outer tube (104) and the cartridge tube (106). The lower end (108L) of the fork pipe (108) is secured with the axle clamp (116) by threaded joinery. A dust seal (120) is fitted at the lower end (104L) of the outer tube (104), and in-between the inner peripheral surface of the lower end (104L) of the outer tube (104) and outer peripheral surface of the fork pipe (108) so as to prevent the ingress of dust and any other foreign particles inside the fork leg.

[0023] Referring to Figs. 4a and 4b, the spindle (110) is configured to have an upper end (110U) and a lower end (110L). The upper end (110U) of the spindle (110) is fitted with a piston assembly (P1), a magnet (M1) and a coupling member (C1). The piston assembly (P1) is comprises of a main body (130), a seal ring (132) and a piston ring (134) and said seal ring (132) and piston ring (134) are fitted in their respective grooves (g1 and g2) provided therefor. The lower end of the main body (130) has a collar (136) followed by a cylindrical portion (138) in axial direction. The said cylindrical portion (138) is projected opposite to the collar (136). The outer diameter of the cylindrical portion (138) is equal to the inner diameter of the upper end (110U) of the spindle (110) but less than the diameter of the collar (136). The outer peripheral surfaces of the collar (136) and the cylindrical portion (138) are provided with a plurality of threads thereon. The upper end (110U) of the spindle (110) is detachably fitted with the cylindrical portion (138) of the main body (130) of the piston (P1).

[0024] Referring to Figs. 5a and 5b, the coupling member (C1) has a cylindrical profile with ‘L’ shaped cross section in such a way that the outer peripheral surface of the coupling member (C1) has flat radial surface and the inner peripheral surface of the coupling member (C1) has step profile forming ‘L’ shaped section. The ‘L’ shaped section of the coupling member (C1) is configured to have a plurality of threads on the inner peripheral surface of stem portion (140) and the base portion (142) of the ‘L’ section has flat surface projecting inward in radial direction. The inner diameter of the stem portion (140) is greater than the inner diameter of the base portion (142) of the L section. The coupling member (C1) is fitted over the collar (136) of the main body (130) of the piston assembly (P1) through a threaded joinery wherein the threads on the inner peripheral surface of the stem portion are meshed with the threads on the outer peripheral surface of the collar (136) of the piston assembly.

[0025] The magnet (M1) is a solid body with an opening (148C) at its center to pass the spindle (110) through it. The upper face (148U) of the magnet (M1) is configured to have a circular projection (150) around the periphery of said central opening (148C) forming a stepped profile at its upper face (refer Fig. 5a). The diameter of the main body (148) of the magnet (M1) is slightly less than the inner diameter of the cartridge tube (106) so as to avoid the friction between the magnet (M1) and the inner surface of the cartridge tube. The said magnet (M1) is sleeved over the spindle inside the cartridge tube (106) and gets fitted with the piston assembly with the projection of the magnet getting fitted in the gap between the base portion of the coupling member and the outer peripheral surface of the spindle by interference fitting. The magnet (M1) may also be fitted with the piston assembly (P1) at its collar by any other suitable fixing means selected from press fitting, intermediate fitting, bush fitting, and using a threaded joint, adhesives and/or combination thereof. The interference fitting of the magnet (M1) with the piston assembly (P1) at the top end of the spindle (110) allows the magnet (M1) to move along with the piston assembly (P1) inside the cartridge tube (106). The said magnet (M1) is of the grade selected from N35, N38, N40, N45, N50, N52. Thus, the magnet (M1) is movable in axial direction of the spindle along with the piston assembly (P1).

[0026] The upper end (110U) of the spindle (110) fitted with piston assembly (P1) along with the magnet (M1) is slideably positioned inside the cartridge tube (106) through the lower end (106L) of said cartridge tube. The lower end (110U) of the spindle (110) is removably fitted at the lower end (108L) of the fork pipe (108) in the axle clamp (116) through an adapter (114).

[0027] The lower end (106L) of the cartridge tube (106) is configured to accommodate a piston assembly (P2) in its stepped profile (106SP) and said piston assembly is fitted there through the threaded joinery. The magnet (M2) is positioned inside the non-threaded portion (106B) of the stepped profile of the cartridge in such a way that it gets locked there with the help of shoulder (106C) of the stepped profile followed by the screwing of the piston assembly (P2) in the threaded portion (106A) of the step profile (106SP). The magnet (M2) has a solid cylindrical body with an opening (152) at its center to pass the spindle through it. The inner peripheral surface (152) of the magnet (M2) is fitted with a plastic sleeve (156) and said sleeve is fitted with said magnet by press fitting. The said plastic sleeve (156) is placed so as to block/shield the magnetic field of the magnet (M2) so that spindle (110) can reciprocate without any friction in the said opening (152) of the magnet (M2). The sleeve (156) is not limited to the plastic, it may be selected from the any of the suitable material that are used to block/shield the magnetic field. The central opening (148C) of the magnet (M1) and the central opening (152) of the magnet (M2) are concentric.

[0028] The outer peripheral surface (152) of the magnet (M2) has plain surface so as to get tightly fitted inside the non-threaded portion of the stepped profile (106SP) and abuts against the shoulder (106C) provided at the lower end of the cartridge tube (106). The magnet (M2) can also be fitted with the piston (P2) by other fixing means selected from press fitting, intermediate fitting, bush fitting, and using a threaded joint and/or combination thereof. The magnet (M2) is fitted at lower end (106L) of the cartridge tube (106) is stationary along with the piston assembly (P2) within cartridge tube (106). The said magnet (M2) is selected from any of the grade of N35, N38, N40, N45, N50, N52. Thus, the magnet (M2) is fixed/stationary along with the piston assembly (P2) inside the cartridge (106).

[0029] After positioning the magnet (M2) inside the step profile (106SP) of the lower end (106L) of the cartridge tube (106), the piston assembly (P2) is securely positioned inside the threaded portion (106A) of the step profile (106SP) and abuts over the over the magnet (M2). The said piston assembly (P2) is comprises of a main body (160), two seal ring (162), an o-ring (164) and a clip ring (166) and said seal rings (162) are positioned in their respective grooves (g3) which are spaced apart at inner periphery of the main body (160) of the piston (P2). The main body (162) of the piston assembly (P2) is configured to have threads on its outer peripheral surface so as to fit said piston assembly (P2) inside the threaded portion (106A) of the stepped profile (106SP) of the cartridge (106). The o-ring (164) is provided between inner surface of the lower end (106L) of the cartridge tube (106) and the outer periphery of the main body (160) of the piston (P2), for restricting the leakage of the working fluid from the cartridge tube (106). Further, the clip ring (166) which is made of plastic/rubber is provided on the lower face of the piston (P2) to avoid metal to metal contact and thereby friction with the fork pipe (108).

[0030] The magnet (M1) fitted to the lower surface of the piston (P1) at its collar and the magnet (M2) fitted over the upper face of the piston (P2) inside the cartridge tube (106) of the leg (A). The magnets (M1 and M2) are fitted at their respective locations in such way that the like poles of the magnets are facing each other. The magnets (M1 and M2) deployed in the leg (A) of the suspension system (500) are configured to have properties such that the magnetic repulsion force (F) is more than the required repulsion force.
F = (µ m1 m2) / (4 p r2)
Where, µ : Permeability constant
r : Distance between the pole
m : Pole strength
The poles (m) are considered as point magnetic poles.
This can be achieved by at least N35 magnet grade with the properties of magnet viz. Hc = 954930 A/m and Br = 1.26 T, and/or any grade of NdFeB magnet wherein Hc is the coercivity of the magnet and is usually measured in oersted or ampere/meter units and Br is the Residual induction (or flux density) of the magnet.

[0031] The fork leg (B) comprises of an outer tube (204) and a fork pipe (208) wherein the fork pipe is slidably movable inside the outer tube. The fork pipe is fitted with the axle clamp and said fork pipe houses a cartridge tube (206) concentrically positioned therein and fitted with the axle clamp (216) over the base tap (222) and said base tap is bolted with the axle clamp. The other end of the cartridge tube is closed with the adapter and at its upper end said cartridge houses a piston valve assembly (P3) which is fitted at the lower end of the piston rod. The rebound spring (202) is positioned in between the piston valve assembly (P3) and the adapter (203). The cartridge tube (206) is filled with the damping fluid preferably selected from oil, gas and air; said cartridge tube is configured to have damping openings to pass the oil from the cartridge tube to fork pipe and the outer tube during compression and rebound strokes.
[0032] The outer tube (204) of the fork leg (B) at its upper end is fitted in the screw cap (212) and houses a piston rod (210) and a main spring (224) concentrically placed around it. The one end of the piston rod (210) is rigidly fitted in the screw cap (212) at its upper end and its lower end is fitted with the piston valve assembly. The main spring (224) rests between the adapter bush (203) and the screw cap (212) concentric with said piston rod (210). Further, the piston rod fitted with a spring guide (226) at its upper portion so as to guide and maintain the position of the main spring (224) concentrically thereon. Also it prevents the buckling of the main spring inside the outer tube. The outer tube is also filled with the damping fluid preferably oil and the main spring is submerged in the damping fluid.

[0033] In an another embodiment of the invention, the piston (P1) fitted at the upper end (110U) of the spindle (110) and the piston (P2) fitted inside the lower end (106L) of the cartridge tube (106) inside the leg (A) are made of magnetic material as specified above and they are configured to orient in such way that the like poles of these magnetic pistons are facing each other. The position of the fork legs (A and B) is reversible within the system without affecting the damping performance.

[0034] As far as the working of the suspension system of the present invention is concerned, when the two wheeled vehicle is subjected to irregularity of road or uneven road surface, the fork assembly will be compressed and decompressed. During the compression stroke, the outer tube (104, 204) of the fork leg A and fork leg B will slide downside over the fork pipe (108 and 208). At this time in the fork leg B, the main spring undergoes compression making the damping fluid to pass from cartridge tube through its piston valve assembly and damping orifices into the fork pipe and the outer tube. In this case the leg B will work as the functional leg and the leg B will work as the follower leg. During the rebound stroke, the main spring of the leg B gets decompressed and relaxed. At this time, the damping fluid from the outer tube and the fork pile passes into the cartridge through the piston valve assembly and the damping orifices provided on the cartridge tube causing the rebound damping. The rebound spring provided between the adapter and the piston valve assembly is used to carry the extra load and provide cushioning during the compression and rebound stroke. As the fork leg A follows the fork leg B, said cushioning effect is being compensated by a pair of magnets (M1 and M2) wherein the magnet M1 is movable along with the piston assembly (P1) and the magnet M2 is in stationary condition along with the piston assembly (P2) to generate a repulsive force in order to provide cushioning and smooth handling.

[0035] Thus, in this invention of hybrid structure of front fork suspension system wherein the leg (B) of the inverted front fork suspension is having a regular construction with the main spring, spring guide, rebound spring and cartridge tube in a fork pipe and the leg (A) has magnet (M1 & M2) based rebound damping with the cartridge tube in the outer tube without requiring main spring, spring guide, damping fluid. Unique placement of magnets (M1 & M2), one fitted at lower side of the sliding member (piston) and other rigidly fixed at inner surface of the lower end (106L) of the cartridge tube (106) imparts progressive repulsion as required for cushioning, leads elimination of NVH, provides improved reliability and improved damping life. This contributes to the technical advancement of the front fork suspension system, particularly for inverted front fork suspension system.

[0036] The technical advancements and advantages derived from the novel features of the embodiments of the present invention as disclosed and described above are as follows:
- The system disclosed by the present invention is quite efficient for rebound cushioning and compression cushioning operation (rebound stroke length of 0 to 40 mm).
- Hybrid arrangement imparts progressive repulsion as required for cushioning and smooth landing.
- No NVH issue due to progressive cushioning.
- The magnets employed in the system attract metallic contaminations, if any, thereby improving damping life of the fork.
- It improves reliability / repeatability.
- Makes the structure light weight as there is elimination of components viz. main spring, spring guide, adjuster tube/spindle, etc.

[0037] It must be noted that the disclosed invention hence achieves all its stated objectives. It provides a technologically advanced hybrid construction of the inverted front fork suspension and enables progressive repulsion as required for cushioning and smooth landing. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. ,CLAIMS:We Claim

1. A hybrid front fork suspension system for a two-wheeler comprising of a fork leg ‘A’, a fork leg ‘B’, a triple clamp bracket (10), and a steering shaft (12); wherein
- The fork leg (A) comprises of an outer tube (104), a cartridge tube (106), a fork pipe (108), a spindle (110), a screw cap (112), an adapter (114), an axle clamp (116), a first piston assembly (P1), a second piston assembly (P2), a first magnet (M1) and a second magnet (M2); wherein
- the cartridge tube (106) is concentrically placed inside the outer tube (104) and is rigidly fixed with the screw cap (112) at the inner peripheral surface of its skirt (112S) through a threaded joinery;
- the lower end (106L) of the cartridge tube (106) is configured to have a stepped profile (106SP) on its inner peripheral surface and said stepped profile (106SP) is configured to have a threaded portion (106A), non-threaded portion (106B) and a shoulder (106C);
- the fork pipe (108) is slideably fitted inside the outer tube in such a way that upper end (108U) of the fork pipe (108) is configured to freely travel in the gap (G) between the outer tube (104) and the cartridge tube (106) and the lower end (108L) of the fork pipe (108) is secured with the axle clamp (116) by threaded joinery;
- the upper end (110U) of the spindle (110) is fitted with a piston assembly (P1), a magnet (M1) and a coupling member (C1);
- the lower end (106L) of the cartridge tube (106) is configured to accommodate a piston assembly (P2) in its stepped profile (106SP) and said piston assembly is fitted there through the threaded joinery and the magnet (M2) is positioned inside the non-threaded portion (106B) of the stepped profile of the cartridge in such a way that it gets locked there with the help of shoulder (106C) of the stepped profile followed by the screwing of the piston assembly (P2) in the threaded portion (106A) of the step profile (106SP);
- the fork leg (B) comprises of an outer tube (204) and a fork pipe (208) wherein the fork pipe is slidably movable inside the outer tube and said fork pipe is fitted with the axle clamp and said fork pipe houses a cartridge tube (206) concentrically positioned therein and fitted with the axle clamp over the base tap (222) and said base tap (222) is bolted with the axle clamp; the other end of the cartridge tube is closed with the adapter (203) and at its upper end said cartridge houses a piston valve assembly (P3) which is fitted at the lower end of the piston rod (210); the rebound spring (202) is positioned in between the piston valve assembly (P3) and the adapter (203); the outer tube (204) of the fork leg (B) at its upper end is fitted in the screw cap (212) and houses a piston rod (210) and a main spring (224) concentrically placed around it; the main spring (224) rests between the adapter bush (203) and the screw cap (212) concentric with said piston rod (210); and said piston rod is fitted with a spring guide (226) at its upper portion so as to guide and maintain the position of the main spring (224) concentrically thereon; and
- the fork legs (A) is joined with the fork leg (B) through the triple clamp bracket (10) to form a hybrid inverted front fork suspension system (500) and said system is connected with the handle bar of a two wheeled vehicle through the steering shaft (12).

2. The hybrid front fork suspension system for a two-wheeler as claimed in claim 1, wherein
- the coupling member (C1) has a cylindrical profile with ‘L’ shaped cross section in such a way that the outer peripheral surface of the coupling member (C1) has flat radial surface and the inner peripheral surface of the coupling member (C1) has step profile forming ‘L’ shaped section;
- the ‘L’ shaped section of the coupling member (C1) is configured to have a plurality of threads on the inner peripheral surface of stem portion (140) and the base portion (142) of the ‘L’ section has flat surface projecting inward in radial direction;
- the inner diameter of the stem portion (140) is greater than the inner diameter of the base portion (142) of the L section; and
- the coupling member (C1) is fitted over the collar (136) of the main body (130) of the piston assembly (P1) through a threaded joinery wherein the threads on the inner peripheral surface of the stem portion are meshed with the threads on the outer peripheral surface of the collar (136) of the piston assembly.

3. The hybrid front fork suspension system for a two-wheeler as claimed in claim 2, wherein
- the magnet (M1) is a solid body with an opening (148C) at its center to pass the spindle (110) through it;
- the upper face (148U) of the magnet (M1) is configured to have a circular projection (150) around the periphery of said central opening (148C) forming a stepped profile at its upper face;
- said magnet (M1) is sleeved over the spindle inside the cartridge tube (106) and gets fitted with the piston assembly with the projection of the magnet getting fitted in the gap between the base portion of the coupling member and the outer peripheral surface of the spindle by interference fitting in such a way that it allows the magnet (M1) to move along with the piston assembly (P1) inside the cartridge tube (106).

4. The hybrid front fork suspension system for a two-wheeler as claimed in claim 3, wherein
- the magnet (M2) has a solid cylindrical body with an opening (152) at its center to pass the spindle through it;
- the inner peripheral surface (152) of the magnet (M2) is fitted with a plastic sleeve (156) and said sleeve is fitted with said magnet by press fitting.
- the outer peripheral surface (152) of the magnet (M2) has plain surface so as to get tightly fitted inside the non-threaded portion (106B) of the stepped profile (106SP) and said magnet (M2) abuts against the shoulder (106C) provided at the lower end of the cartridge tube (106) in such a way that it is stationary along with the piston assembly (P2) within cartridge tube (106).

5. The hybrid front fork suspension system for a two-wheeler as claimed in claim 4, wherein
- the central opening (148C) of the magnet (M1) and the central opening (152) of the magnet (M2) are concentric; and
- the said magnets (M1 and M2) are of the grade selected from N35, N38, N40, N45, N50, N52.

6. The hybrid front fork suspension system for a two-wheeler as claimed in claim 3, wherein
- the piston assembly (P1) is comprises of a main body (130), a seal ring (132) and a piston ring (134) and said seal ring (132) and piston ring (134) are fitted in their respective grooves (g1 and g2) provided therefor;
- the lower end of the main body (130) has a collar (136) followed by a cylindrical portion (138) in axial direction and said cylindrical portion (138) is projected opposite to the collar (136);
- the outer peripheral surfaces of the collar (136) and the cylindrical portion (138) are provided with a plurality of threads thereon and the upper end (110U) of the spindle (110) is detachably fitted with said cylindrical portion (138) of the main body (130) of the piston (P1).

7. The hybrid front fork suspension system for a two-wheeler as claimed in claim 4, wherein
- the said piston assembly (P2) is comprises of a main body (160), two seal ring (162), an o-ring (164) and a clip ring (166) and said seal rings (162) are positioned in their respective grooves (g3) which are spaced apart at inner periphery of the main body (160) of the piston (P2);
- the main body (162) of the piston assembly (P2) is configured to have threads on its outer peripheral surface so as to fit said piston assembly (P2) inside the threaded portion (106A) of the stepped profile (106SP) of the cartridge (106); and
- the O-ring (164) is provided between inner surface of the lower end (106L) of the cartridge tube (106) and the outer periphery of the main body (160) of the piston (P2), for restricting the leakage of the working fluid from the cartridge tube (106).

8. The hybrid front fork suspension system for a two-wheeler as claimed in claim 5, wherein
- the outer tube (104) is configured to have a cylindrical profile with an upper end (104U) and a lower end (104L);
- the upper end (104U) of the outer tube (104) closed with a removable screw cap (112) through a threaded joinery wherein the outer peripheral surface of the screw cap (112) has a plurality of threads thereon and the inner peripheral surface of the upper end (104U) of the outer tube (104) has a plurality of matching threads; and
- the skirt (112S) of the screw cap (112) is configured to have threads on its inner peripheral surface to get the cartridge (106) fitted therein and on the outer peripheral surface to get the outer tube (104) fitted thereon.

9. The hybrid front fork suspension system for a two-wheeler as claimed in claim 3, wherein
- the cartridge tube (106) is configured to have a cylindrical profile with an upper end (106U) and a lower end (106L);
- the threaded portion (106A) of the stepped profile (106SP) starts from the bottom edge of the cartridge and exceeds more than 60 per cent of the total length of the stepped profile (106SP);
- said non-threaded portion (106B) starts wherein the threaded portion (106A) ends and it goes up to the shoulder (106C).

10. The hybrid front fork suspension system for a two-wheeler as claimed in claim 3, wherein
- The fork pipe (108) is configured to have a cylindrical profile with an upper end (108U) and a lower end (108L); and
- a dust seal (120) is fitted at the lower end (104L) of the outer tube (104), and in-between the inner peripheral surface of the lower end (104L) of the outer tube (104) and outer peripheral surface of the fork pipe (108) so as to prevent the ingress of dust and any other foreign particles inside the fork leg.

Dated this 6th day of Nov. 2023

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.
To,
The Controller of Patents,
The Patent Office, at Mumbai.